1. Field of the Invention
The present invention relates to a load control device for controlling the intensity of a lighting load, specifically a traditional-opening dimmer switch having a single button that causes the load control device to toggle the lighting load when the button is depressed and released, actuates an air-gap switch when the button is pulled out, and provides a visual display that illuminates to display a representation of the intensity of the lighting load when the load is on and a night light when the load is off.
2. Description of the Related Art
A conventional wall-mounted load control device is mounted to a standard electrical wallbox and is connected in series electrical connection with an electrical load. Standard load control devices, such as dimmer switches and motor speed controls, use one or more semiconductor switches, such as triacs or field effect transistors (FETs), to control the current delivered from an alternating-current (AC) power source to the load, and thus, the intensity of the lighting load or the speed of the motor.
Wall-mounted load control devices typically include a user interface having a means for adjusting the intensity or the speed of the load, such as a linear slider, a rotary knob, or a rocker switch. Some load control devices also include a button that allows for toggling of the load between off (i.e., no power is conducted to the load) and on (i.e., power is conducted to the load). It is often desirable to include a plurality of status indicators, such as light-emitting diodes (LEDs), on the user interface to indicate the intensity or speed of the load.
FIG. 1 shows the user interface of a prior art dimmer switch 10 having a plurality of status indicators 20. As shown, the dimmer switch 10 includes a faceplate 30 (i.e., a cover plate), a frame 32, an enclosure 34, a toggle button 40, and an intensity selection actuator 50 for selecting a desired level of light intensity of an associated lighting load controlled by the dimmer switch. The button 40 comprises an infrared (IR) lens 60 for receiving IR signals transmitted from an external IR transmitter (not shown) to control the intensity of the connected lighting load. The dimmer switch 10 further comprises an air-gap switch actuator 70 for actuating an air-gap switch inside the dimmer switch to provide an actual air-gap break in the electrical connection between the source and the load.
Pressing the button 40 causes the associated lighting load to toggle from on to off, or vice versa. Actuation of the upper portion of intensity selection actuator 50 increases or raises the light intensity of the lighting load, while actuation of the lower portion of actuator 50 decreases or lowers the light intensity. The intensity levels of the lighting load may range from a minimum intensity level, which is preferably the lowest visible intensity, but may be zero, or “full off,” to a maximum intensity level, which is typically “full on.” Light intensity level is typically expressed as a percent of full intensity. Thus, when the lighting load is on, the light intensity level may range from 1% to 100%.
The dimmer switch 10 also includes an intensity level indicator in the form of the plurality of status indicators 20 located on the frame 32. The status indicators 20 may be arranged in an array (such as a linear array as shown) representative of a range of light intensity levels of the lighting load being controlled. The linear array of status indicators 20 represents a linear scale (between off and full intensity of the associated lighting load), such that one of the status indicators is illuminated to indicate the intensity of the lighting load. For example, if the dimmer switch 10 is controlling the lighting load to 50%, the middle status indicator will be illuminated, since this status indicator is at the midpoint of the linear array of the status indicators 20.
Another example of a dimmer switch having a linear array of status indicators is described in U.S. Pat. No. 5,248,919, issued Sep. 28, 1993, entitled LIGHTING CONTROL DEVICE, the entire disclosure of which is hereby incorporated by reference.
In order to keep the pressure required to actuate the toggle button less than the maximum comfortable pressure for a human finger, it is desirable to maximize the front surface area of the toggle button. Therefore, there is a need for a traditional-style dimmer switch that comprises a button having a maximum surface area, while still providing all of the functionality and features of the prior art dimmer switch 10, i.e., the toggle functionality of the toggle button 40, the air-gap actuator 70, and the linear array of status indicators 20.